Photos do not lie, so I must stand corrected. Apparently your Zebra has adapted quite well to the direct sun you have provided. Yours is one of the healthier older Zebras I have seen.
What leaves you have lost were undoubtedly a result of the occasional episodes of drought, which is what you had suggested in your original question.
I wish I had just said, "Yes," and left it at that instead of pontificating as I am oft inclined to do. Thank you for puncturing my pomposity - I need that from time-to-time!
If you have any questions about Zebra plants
, please contact Cricket.